const exec = require('child_process').exec;
var arr = 0;

exec('head -n 80 /dev/urandom | tr -dc A-Za-z0-9 | head -c 168',
  function(err,stdout,stderr){
    arr = stdout;
    session[arr] = 123;
    console.log(arr);
  }
);

console.log(session);
